Hydraulic power lift for tractor apparatus



Nav. 4, 1947. F. w. WELLS Er Al. 2,430,197

HYDRAULIC POWER LIFT FOR TRACTOR APPARATUS Filed Feb. 27, 1942 3 Sheets-Sheet l Nov. 4, 1947. F. w. WELLS Em.

HYDRAULIC POWER LIFT FOR TRACTOR APPARATUS Filed Feb. `27,` 1942 3 Sheets-Sheet 2 Y XW ATTORNEY l HYDRAULIC F. w. wELLs 'ET A1. 2,430,197

PowER LIFT RoR TRAcToR APPARATUS Filed Feb. 27, 1942 I 3 Sheets-Sheet 5 INVEN'I'OFKS ATTORNEY Patentes Nov. 4, 1947 2,430,197

HYDRAULIC POWER LIFT FOR-TRACTOR APPARATUS Frank W. Wells and Joseph T. lulln'tvy,` Rock Island, Ill.

Application February 27, 1942, Serial No. 432,670 2 Claims. (Cl. 60-52) The present invention relates to power lift apin Fig. 1, taken on the line 5-5 of Fig. 2, and paratus and particularly to such apparatus as is showing a modified arrangement, adapted for application to tractors. and an ob- As seen in Fig. 1. the invention comprises a casject of the invention is to generally improve the ing or housing 5 which may be bolted or otherwise construction and operation of devices of this 5 fixed on atractor (not shown) in any convenient class. More particularly the invention relates to location to become a part thereof. Housing 5 power lifts which are actuated by fluid pressure l serves to enclose the mechanism of the power lift and a further object of the invention is to provide proper and also as a reservoir for fluid. A shaft 6 such a power lift operating upon a new and novel which may be. for example, a power take-olf shaft principle. l extending from the tractor in any convenient or A further object of the invention is to provide well-known location, traverses housing and is expedients for the accomplishment of the novell supported therein in anti-friction or other suitobjects. able bearings as 1,y an oil seal of suitable or well- Further objects are to provide such a power lift known type 8 being provided for the usual purhaving a pump which operates only while power l5 poses, it being desirable to locate housing 5 at lifting operation is actually in progress and which such a point on the tractor that one of the well is entirely stationary at other times; such a power known externally projecting power shafts comlift which while subject to manual control at any monly provided will pass through the housing 5 point in its cycle nevertheless will cease operato serve as shaft 6. Shaft 8 actuates a pump unit tien at a predetermined point regardless the ac- 2o generally designated as l which forces fluid from tuation of the manual control; such a power lift reservoir 5, when desired, into/a ram cylinder IIJ in which implements or objects lifted by the for accomplishing the usual purpose of a power power lift may be held at any point in the lifting lift, the fluid returning to reservoir 5 through an movement or in the lowering movement; and such outlet valve generally designated as I l when it is a construction in which undue wear on the parts desired to lower the implements or objects conis virtually eliminated. nected with the lift. In the event that excessive A further object is to devise such a power lift pressure is developed for any reason by the acproviding a permanently located lifting element, tion of pump 9, this is relieved by a, relief valve but which is adapted to h ave one or more addigenerally designated as I2 and control means gentional lifting elements at a distance from said 10- 30 erally designated as I3 operate to start and stop cation. the actuation of pump '9 by shaft 6 and also to A further object is to provide such a power lift actuate outlet valve Il, control means I3 being which may be actuated from any convenient adapted to automatically return to a neutral popower shaft normally in the tractor for another sition whenever released. whereupon pump 9 purpose. stops and any implement connected with the Further objects and advantages of the invenpower lift remains in status quo. e

tion will become apparent from a, consideration Returning to a more detailed description of the of the following detailed description taken in conconstruction, housing` 5 comprises a shell-like nection with the accompanying drawings wherein member or casting having an open side closed by a satisfactory embodiment of the invention is 40 a cover plate I4 which may be removed for access shown. However, it is to be understood that the to the interior. invention is not limited to the details disclosed Most of theoperative parts are supported on but includes all such variations and modifications and carried by housing 5- F 01' example Dump 9 es fen within the spirit e1 the invention as nerein the Present instance comprises Plmgers '5 and I6, Fig. 2, reciprocable in suitable bores in hous j n' expressed' m the annexed drawings ing 5, in the present instance in a substantially Figure 1 is avertical sectional view of an iilushorizontal posmon The bores Isa and ma for trative embodiment of the invention. l

plungers l5 and I6 may be formed through suit- Fig. 2 is a sectional view taken on the line 2-2 t of Fig. 1, with parts broken away. able openings in housing 5 closed by plugs Il and It. Since lun ers I5 and I6 1 Fig. 3 is an enlarged detail of certain mechp g are dentlcal in onl one will b anism indicated in Fig. 1. scribed in detail. y e de Fig. 4 is a similar view of another portion of As seen in Fig. i, plunger i6 has pivotally con- Fig. 1. nected thereto as by a pin i9. a link 20 in turn Fig. 5 is a view of a part of the structure shown 55 pivotallyA connected as by a pin 2| with an arm circuit is described.

22 of a bell crank generally designated as 23. Bell crank 231s journaled on a shaft 24 supported in housing in any suitable manner and 'has an arm 25 carrying a roller 26 which may engage a cam element, eccentric, or other recipro-l cating or pulsating mechanism 21 fixed with above mentioned shaft 6. Other suitable or wellknown cam follower means is-contemplated as equivalent to roller 26 and theV invention is not to be taken as limited to the use of a roller, or in fact in any manner except as defined in the claims.. Bell crank 23 also has an arm 21a to which is connected "in the present instance a spring 28 by an anchorage 29 of a character such that spring 28 may exert a downward or an upward`force against arm 21a at will. A similar anchorage 30 is provided for the opposite end of spring 28 to connect the same to above mentioned control means I3, the function of which will be more easily understood after the hydraulic As shown in Fig. 1, spring 28 is in compression and tends 'to-rotate bell crank 23-.in a counter-clockwise direction. Rotation of shaft 6, as will be apparent, repeatedly rocks bell crank 23 in a clockwise direction against the compression of spring 28, the expansion of the spring causing the return movement of bell crank 23 so that roller 26 will follow cam member 21. This causes reciprocating or pumping movement of plunger I6 as will be apparent.

Anchorage 38 is xed with a plate 3l which is ilxedly connected with a rod` 32 forming a part of control means I3 and extending upwardly through a guide portion 33 in housing 5. Rod 32 in the present instance has a spring 34 compressed between housing 5 and an abutment 35, nxed relatively to the rod by a pin or other suitable means 36. In the position of the parts shown, spring 34 has been overcome by the clockwise rotation of a hand lever generally designated as 31 fulcrumed at 38 on an anchorage 39 supported on the tractor at any desired or convenient point. Lever 31 has an arm 40 pivotally connected by a link or other appropriate means 4I with above mentioned rod 32. Spring 34 is so proportioned as to raise rod 32 upon release of lever 31, plate 3I sliding upwardly on a guide rod 42, xed within housing: 5, to dotted position A at which point spring 28 is no longer in compression but is in tension. Plunger I6 upon completion of a stroke by. action of cam 21 on bell crank 23, will take a position at its innermost poin-t in bore I6a and will remain stationary and pump no more fluid.

Plunger I5 is actuated in the present instance in an identically similar manner from a cam 21h actuating a bell crank 23a identical with bell crank 23, and the parts being returned by a spring 28a connected to an arm 21o on bell crank 23a. Plunger I5, of course, also goes out of operation as above mentioned, and the action of pump 9 ceases.

The innermost position taken by plunger I6 will be such that cam 21 may lightly contact roller 26 upon each revolution of shaft 6, resulting in a slight ticking sound and possibly unnecessary wear on the parts. This may be avoided by any means allowing the escape of fluid from bores I5a and IBa, in the present instance valve unseating devices generally designated as 43-43a.

For a full understanding of this expedient, it is necessary to describe the fluid passageways at this point. A bore 44 extends from above mentioned cylinder bore I6a into a bore 45 constituting a pump valve chamber, Bore 45 has therein passageways,

an intake valve'in the present instance in the form of a ball 46 seated against a shoulder 41 by means of a spring 48 engaged between the ball and an abutment 49 of any suitable type. Shoulder 41 is defined between above mentioned bore 45 and a bore 59 forming the intake port for valve 46. An outlet or exhaust valve 5I is seated against a shoulder 52 defined between above mentioned bore 45 and a bore 53. Ball 5I is maintained against its seat by Ia spring 54 compressed between ball 5I and a plug 55 threaded or otherwise secured in bore 5I It will be understood that a precisely similar arrangement is associated with above mentioned plunger I5, an inlet valve 46a', Fig. 5, being seated against a shoulder 41a formed between a bore 45a and a bore 59a, and an outlet valve 5Ia being seated against a shoulder 52a formed between bore 45a and a bore 53a, constituting an outlet chamber for pump cylinder I5a. Outlet chamber 53a corresponding to bore 53 is communicated or connected with bore 53 by a bore 56. A two-cylinder single acting pump is therefore provided by the utilization of connecting drilled or otherwise suitably formed in a portion of the wall of housing 5.

.In the present instance leading from bore 5I is'a bore 51. A non-return or check-valve 58 is seated on a shoulder 59 dened between above mentioned bore 51 and a bore 60 leading to the exterior of housing 5 and the end of which is closed in the present instance by a removable plug or the like 6I. Valve 58 is seated by means of a spring 62 compressed between the valve and an abutment 53 of any suitable type.

A bore 64 leads upwardly from bore 6I! into above mentioned ram cylinder I9 and in the present instance is threaded at 65 to provide for blocking of the bore when desired, and a bore 66 opposite bore 64 is closed by a plug 61 upon the removal of which access may be had to threaded portion 65 of bore 64.

It will now be apparent that reciprocating movement of plunger I6 will cause pumping of fluid inwardly through bore 58 past valve 46 and expelling o fluid past valves 5I and 58 into bore 60 and ti. ence through bore 64 into ram cylinder ID.

In the present illustrative embodiment, a, bore 68 leads upwardly out or above mentioned bore 69 and denes a shoulder '69 between itself and a bore 16. An outlet valve 1I is seated against shoulder 69 by a spring 12 encompassing a pin 13 or extension of an adjusting screw 14 threaded into housing 5. Valve 1I accordingly normally remains seated on shoulder 69 and prevents escape of fluid from bores 68 and 68. Ball 1I, however, may be unseated by a finger 15 as will be presently apparent,

Relief Valve I2 operates from bore 68 as follows. A bore 16 extends from bore 68 defining a shoulder 11 between itself and a bore 18'extending to the exterior of housing 5. A ball valve 19 is seated against shoulder 11 by a tting 89, a spring 8|, and a screw 82, in the present instance threaded in housing 5. In this manner a relatively high unit pressure may be secured against a valve having a relatively small area exposed to fluid pressure. A bore 83 leads from bore 18 into the interior of housing or reservoir 5. Thus in the event excessive pressure is developed by pump 9, ball 19 will be forced away from shoulder 11 and fluid will escape through bores 16 and 83 and return to reservoir 5. In the presvwent instance, spring 8| is so compressed that this will occur normally when the desired limit of power lift movement is reached until such time as lever 31 is released.

A box like screen element 83a is preferably disposed over elements 43. and 43a, being fixed to housing 5 by a flange 83D clamped by a. screw or the like 83o.

By virtue of the fact that fluid is pumped only during the time that lifting is actually ybeing accomplished, there is no difficulty from heating of the fluid, and as a result, pump 9 and cylinder I may be made substantially larger in volumetric capacity than would be the case with any kind of a continuously pumping hydraulic circuit. As a result the present lift will perform a given lifting task with a correspondingly smaller fluid pressure than power lifts of known type. The pressure at which relief valve I2 is set to open need not be greatly in excess of the maximum pressure necessary to perform the work of the lift, and in no case is it suiciently high to cause any undue stress in the parts. Thus, while valve I2 operates as an emergency relief valve, it is not exclusively an emergency valve, and actually operates for a short time each time the lift is operated. This tends to keep it in good operating condition so that it will not fail in case an emergency does arise. Furthermore, owing to the relatively low working pressure, no undue heating of the fluid will occur even if the relief valve operates longer than normal, as in the case of an inexperienced operators holding lever 31 in the working position after the power lift has completed its lifting stroke.

Screw 82 may be adjusted to arrive at the desired degree of compression of spring 8|. Also screw 14 may be adjusted to provide for a desired amount of clearance between pin 13 and valve 1| so that the degree of opening of valve 1I may be positively controlled. In this way the return or dropping of implements or other objects acted upon by the power lift may be definitely predetermined, as will appear.

Returning to unseating device 43, as more particularly shown in Fig. 3, the device comprises a shell 84 having a large bore 85 within which is reciprocable a guide portion 86 of an unseating pin 81. Inlet bores B1a-81a provide for entrance of fluid into the shell and accordingly into bore 50. Guide portion 86 is forced upwardly by a spring 88 against a stop 89 of any suitable type, in the present instance anchored in a flot or slots 90 in shell 84. Guide 86 has an abutment 9| extending upwardly for actuation by a finger 92.

`Finger 92 presses downwardly upon abutment 9| forcing the parts to the dotted position shown whereupon valve 46 is forced away from shoulder 41 thereby relieving the pressure in pump cylinder bore Isa, as will be apparent from Fig. 1.

Finger 92 has a counterpart 93, the two being united by a portion 94 connected with a lever 95. Lever 95 is fulcrumed on a pin 96 carried on a support 91 threaded or otherwise anchored in housing as at 98.

Lever 95 is actuated by a tension spring 99 connected between lever 95 and above mentioned plate 3| in any suitable manner. As will now be apparent, when lever31 is released, spring 34 will expand, raising rod 32 and causing a tension in spring 28, and also a tension in spring 99. This will rock lever 95 and fingers 92 and 93 in a counter-clockwise direction as seen in Fig. l, thereby pushing down unseatingpin 81 and its companion pin 81h, Fig. 5, associated with plunger I5. The several springs 34, 28, 28a, 99, 88, 88a, 48 and 48a are so proportioned that springs 28, 28a and 99 will be tensioned and springs 88, 88a, 48, and 48a will be compressed by the expansion of ,spring 34 when lever 31 is released, and plate 3| takes position A. Pressure in the pump cylinders will be released and the tension in spring 28 will produce the extreme inward position of plunger I6, the same thing happening in plunger I5 as will be understood. This removes bell cranks 23 and 23a from the path of movement of cams 21 and 21b and avoids any .known type |02. A head |03 is fixed to rod IOI and extends to one'side where it is fixed with a guide rod |04, slidable in a guide portion |05 in the present instance forming part of housing 5.

In this manner piston |00 is definitely guided independently of cylinder I ilv so that any side thrust reaction occasioned by implements connected to be lifted or the like is taken by guide rod |04 rather than the walls of cylinder I0; Unduc wear of the cylinder is thereby eliminated.

To minimize such side thrust, a connection to elements to be lifted is provided in the present instance in the form of a rock shaft I 06 journaled in a suitable bearing |01 xed with the tractor.

Any well-known connection from rock shaft |06r to the various implements which it is desired to lift may -be provided as will readily be understood by one skilled in the art. Rock shaft |06 has a b-ifurcated arm |08 extending to a region above piston rod I0| at which point it is pivotally connected with a thrust block |09 by a pin or the like IIO. Thrust block |09 is pivotally connected as by a pin I I I with a blfurcated or suitable guide arm I|2 pivoted at I|3 in the present instance to above mentioned bearing |01. Thrust block |09 has a face II4 preferably at right angles to piston rod |0I and head |03 is provided with an anti-friction abutment, for example, a roller IIS in contact with face' I I4.

In the present arrangement, pivots I I0 and I I I are disposed in a plane parallel to rod IUI. Rock shaft |06 and pivot |I3 are also disposed in a plane parallel to shaft |0I arm I08'and guidearm ||2 being of equal length. Consequently, during swinging movement of arm |08 and guide arm I I 2, block |09 will in all positions remainparallel Therefore, since face |I4 is at substantially right angles to rod IOI, the reaction on rod IOI will always be axial to the rod and no side thrust will 'be developed by the rod I0 against block |09. Any side thrust developed by friction roller II5 is taken up by guide rod |04. Other arrangements which will insure that face I I4 will remain perpendicular to rod 0I are contemplated as within the scope of the invention.

It will now be apparent that clockwise movement of lever 31 will compress springs 34 and 28 and relax springs 99, 88, 48, etc., thereby releasing intake valves 46 and 46a to close, and retracting plungers I4 and I6. If shaft 6 is rotating, plungers I5 and I6 will be reciprocated by cams 21 and 21b and fluid will be pumped through passageway 60 into cylinder I0. This will raise piston |00 and rod |0I and block |09, rocking arm |08 and a rock shaft |06 in a counterclockwise direction. This action will continue as long as lever movement of the pump parts fromthe rotation of l 31 is held in the above" position, but will stop immediately if lever 31 is released, piston |00 being held in Whatever position it has reached by a closing of non-return valve 58. If lever 31 is not released, but continues to be held, will continue to run until piston |l reaches the limit of its movement whereupon pressure in the several passageways will rise to a point to force valve 19 to open against spring 8|, whereupon the fluid pumped will be returned through bore 83 to i reservoir 5. The operator holds lever 31 until this condition occurs, which ordinarily takes only a few seconds, and no complications such as a cyclic clutch trip valve, or other expedients are necessary. Also, as above suggested, if for any reason the operator does not desire to lift the implements to their full extent, he may release lever 31 at any time during the upward movement, whereupon the parts will remain in the position attained.

Lever 31 also functions to allow the implements to drop as follows.

Above mentioned guide rod 42 has a slide block ||6 adjacent the upper end thereof, connected by a link ||1 pivoted to the block at H8, and connected with a. lever generally designated as H9. Lever ||9 is fulcrumed at |20 on a standard or support |2|, xed in any suitable manner with housing 5,. Lever ||9 has an arm |22 connected with link ||1 and also an arm |23 in the present instance bending about cylinder I0. Arm |23 is preferably, although not necessarily, bifurcated at |24 and has a pin |25 pivotally connected to a block |25, carrying above mentioned finger 15.

It will be noted that in position A of plate 3|, slide block ||6 is unaffected. However, counterclockwise movement of lever 31 beyond the position attained by merely releasing thelever will move plate 3| to position B. This is permitted by further extension of springs 28, 28a and 99. Plate 3| in position B raises slide block` H6 and rocks lever H9 in a counter-clockwise direction by means of link |1. This pushes down on nger 15 and unseats ball valve 14 to the extent determined by the position of lever 31, or

permitted by pin 13. Fluid in cylinder |0 there fore escapes from cylinder l0 through bores S4, 60, 58 and 10, allowing piston |00 to fall at the rate determined by the adjustment of screw 14, which as above noted, governs the degree of opening of valve 1| by pin 13.

As in the case of the raising movement of piston` |00 and the attached parts, this lowering movement may be arrested at any desired point by merely releasing lever 31. Plate 3| immediately returns to position "A closing valve 1|. Since pump 9 is inoperative, in this position, piston |00 does not move either way.

Returning to a further description of certain mechanical details, piston |00, as more particularly shown in Fig. 4, is assembled on a. stem portion |21, extending downwardly from above menntioned rod |0| and defining a shoulder |28. A

plate |29 of suitable material, such for example as soft metal, rests against shoulder |28 and guides the piston within the Wall of cylinder ||0 andl is .locked in place against shoulder |28 rin the present instance by a lock nut |30, nut |30 being threaded on stem |21, and provided with openings |3| and |32. for reception of a Spanner or other tool for adjusting it Disposed about lock nut |30 is a hydraulic packing assembly generally designated as |33 and preferably, although not necessarily, of the type known in the trade as Chevron packing. A lock 'nut |34 is also threaded on stem |21 for compressing packing |33 and has openings |35 and |36 to be engaged by a spanner or other suitable instrument for tightening-the nut. Nut |34 exerts its pressure against packing |33 through a washer |31 of spring metal or the like and having an offset configuration, such that it is resiliently yieldable under pressure of nut |34. Therefore, washer |31 will follow up` any shrinkage or normal wear of packing |33 so that it will remain tight during long periods of operation without adjustment.

Cylinder |0 may be secured in housing 5 in any suitable or desired manner, in the present instance the cylinder being seated against a gasket |38 in a counter-bore |39 by means of a nut |40 threaded in a boss |4| in housing 5. Nut |40 carries above mentioned oil retainer |02 and preferably has a bore |42 for receiving the upper end of cylinder I0. Cylinder i0 has a notch or opening |43 communicating with a clearance |44 provided in bore |42 for communication of the space Y above piston |00 with the interior of housing 5. This relieves any pressure or partial vacuum which might otherwise form above piston |00'.

The modification shown in Fig. 5 is designed to be used for such purposes as would not be conveniently served by the location of ram cylinder I0 and piston rod |0| in or on housing 5, the pump and control means disclosed serving as a part of its function to control a similar ram cylnder at a distance from said housing 5. Examples of such use might be where a snow plow, or the like, was mounted in an overhanging position in front of the tractor. Such a plow could be controlled by lever 31 as follows. Plug 0|, Fig. 1, is removed and in its place is inserted a fitting or portion |45, Fig. 5, of a. ilexible or suitable conduit |46 which leads to the desired point of operation. Conduit |45 is connected preferably at |41 to a ram cylinder generally designated as |48 which may be constructed along the lines of above mentioned ram cylinders I0 and |00, although any other suitable or well-known construction of ram is considered as within the scope of the invention. In the present instance ram |48 is provided with an anchorage |49, a piston rod |50 and a clevis or other suitable connecting means |5|. Cylinder |48 is anchored by means .of portion |49 on any convenient part of the structure and clevis |5| is connected with a portion of the structure where it is desired to have movement relative to the part to which |49 is fastened. Actuation of lever |31 will then cause actuation of piston rod |50 relatively to cylinder |48 in the manner above described in the case of piston rod |0|, and the attached implement or parts will be controlled in the same manner.

In fact cylinder |48 need not necessarily be located on the tractor within the present invention, but might be for example on an implement drawn by the tractor and which had a part which was desired to be raised and lowered or otherwise adjusted by the operator on the tractor.

When cylinder |48 is in use, if it is desired that cylinder |0 shall become inoperative, plug 61 may be removed and a plug |52 may be inserted in above mentioned threaded portion 65, whereupon cylinder I0 will be blocked from passageway 60. With plug 61 replaced, cylinder |48 and piston rod |50 alone will respond to the control of lever 31.

It is thought the operation of the above described construction will be clearly apparent from the foregoingJt being noted that pump 9 operates only while lifting is actually in progress; that -no attention need be paid to the unit until it is desired, for example, to raise an implement carried by the tractor, all the power lift parts being completely at rest and subject to no wear (assuming shaft 6 to be in the tractor for another purpose, such as a power take-olf or a belt -pulley shaft). When it is desired to lift an implement, lever 31 is grasped and raised or rotated clockwise as seen in Fig 1. Pump 9 immediately goes into action and extends ram piston rod thus lifting the implement through appropriate connections from rock shaft 6. No particular attention need be paid this operation, since when the implement has reached its uppermost position, further movement of piston |00 will be blocked by plug |40 or by implements or other connected load, and

iiuid being pumped will escape through valve |2.

' The operator releases lever 31 when the implement is obviously at its uppermost position, when it is held there by the accumulation of fluid under piston |00. If the operator does not wish the implement to move to its uppermost position, he may release lever 31 at any time during the upward travel when the implement will be held in the new position. This is so because uid cannot return to pump 9 because of non-return valve 58. Of course, the fluid could not get back to the pump cylinder because of outlet valves 5| and 5|a, but non-return valve l58 makes it all the more certain that the fluid will be positively retained and prevent the implements from gradually returning to lowered position.

When it is desired to lower the implement, the

operator presses down on lever-3|, or rotates ity A" counter-clockwise, as seen in Fig. 1, whereupon outlet valve 1| is opened, allowing escape of iiuid from cylinder I0, and dropping of the-implement.

As above noted, this movement may also be arrested at any desired point by releasing lever 31 if it is not desired to lower the implement to its full extent. Both of .these conditions also apply to cylinder |48, in Fig. 5.

As above noted, the rate that the implement drops, may be regulated by adjusting screw 14, to

determine the clearance between valve 1| and the end of pin 13 The above being a complete description of an illustrative embodiment of the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A control means for a hydraulic power lift having a iiuid reservoir, a cam, a reciprocating pump plunger, an inwardly opening intake valve for the pump having a passageway opening out of the reservoir, a ram, a. check valved passageway connecting the pump and the ram, and an inwardly opening relief valveV in the passageway having a port communicating with the reservoir, said control comprising the combination of a spring connected with the plunger and stressable in one direction to yieldably urge the plunger in a direction to be actuated by the cam, said spring being stressable in the opposite direction to urge the plunger away from the cam to inoperative position, manually operable means for so stressing said spring,

for unseating the same, and ram lowering nger means projecting into the passageway 'leading from said relief valve for unseating the same for lowering the ram, and connections from said manually operable means for projecting said unloading nger means into the pump intake passageway for unseating said intake valve upon movement of said control means for stressing said spring in a direction to urge the plunger away from the cam, and to project said ram lowering finger meansl into the passageway leading from the relief valve to the reservoir for unseating the relief valve for lowering the ram.

2. A control means for a hydraulic power lift having a fluid reservoir, a cam, a reciprocating pump plunger, an inwardly opening intake valve for the pump having a passageway opening out of the reservoir, a ram, a check valved passageway connecting the pump and the ram, and an inwardly opening relief valve in the passageway having a port communicating with the reservoir, said control comprising the combination of a spring connected with the plunger and stressable in one direction to yieldably urge the plunger in a REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date ,4 398,784 Joyce Feb. 26, 1889 847,834 Sears Mar, 19, 1907 895,666 Nelson Aug. 11, 1908 1,178,733 Koken Apr. 11, 1916 1,203,323 Gardner Oct. 21, 1916 1,453,043 Erhardt Apr. 24, 1923 1,580,499 Kruttschnitt Apr. 13, 1926 1,644,101 Anderson Oct. 4, 1927 1,788,027 May Jan. 6, 1931 1,799,298 Jakob Apr. .7, 1931 1,868,935 Breneman July 26, 1932 1,881,939 Purdy Oct. 11, 1932 1,920,285 Wilkins Aug. 1, 1933 1,991,453 Giovannoni Feb. 19, 1935 2,037,434 Pfauser Apr. 14, 193.6 2,042,004 Hurst May 26, 1936 2,139,473 Sessions Dec. 6, 2,170,464 Rosenberry Aug, 22, 1939 2,255,984 Pfauser Sept. 16,1941 2,264,560 Albertson Dec. 2, 1941 2,332,629 Frudden Oct. 26, 1943 FOREIGN PATENTS Number Country Date 374,454 Germany 1923 680,063 France 1930 369,761 Great Britain 1932 unloading finger means projecting into the passageway leading to said intake valve 

